| abstract |
Disclosed is a method for producing a relatively high molecular weight copolyester which comprises the steps of (a) melt-phase copolymerizing to an inherent viscosity of about 0.50 to about 1.10 a dibasic acid component and a glycol component, the dibasic acid component consisting essentially of trans-1,4-cyclohexanedicarboxylic acid and the glycol component comprising, from about 97 to about 70 mol percent 1,4-cyclohexanedimethanol, about 3 to about 30 mol percent of a glycol having 2 to 5 carbon atoms and from about 15 to about 80 weight percent of the total polymer of a polyalkyleneether glycol, and (b) solid-phase polymerizing the copolyester from step (a) at a temperature of from about 110 DEG C. to about 200 DEG C. to a higher inherent viscosity of from about 0.60 to about 2.50, the higher inherent viscosity being at least 0.10 higher than the inherent viscosity reached in step (a). Such a process using a particular acid and particular mixture of glycols allows inherent viscosity build-up without use of temperature high enough to cause thermal degradation and the resulting odor and color formation. |